Chinese authorities kill 20,000 birds as avian flu toll rises to 6

By Jethro Mullen, CNN

Updated 1625 GMT (2325 HKT) April 5, 2013

Photos: Bird flu scare spreads37 photos

Bird flu scare spreads – A janitor sprays disinfectant over empty chicken cages at a market in New Taipei City, Taiwan, on Monday, April 29. Asian countries have stepped up vigilance against the spread of H7N9 bird flu after a case of the deadly strain showed up in Taiwan, the first outside mainland China.

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Bird flu scare spreads – A New Taipei City Department of Environmental Protection truck sprays a virus disinfectant in a park on April 29.

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Bird flu scare spreads – Doctors hold a consultation on the treatment for a patient surnamed Luo, the province's first human case of H7N9 avian influenza, at the No. 2 Hospital in Longyan City, in southeast China's Fujian Province, on April 27. Luo, 65, a local resident, showed symptoms of repeated coughing, low fever and a tight chest on April 18. Luo tested positive for the H7N9 virus on Friday by the Chinese Center for Disease Control and Prevention. Thirty-seven people who have been in close contact with Luo have not shown any abnormal symptoms so far.

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Photos: Bird flu scare spreads37 photos

Bird flu scare spreads – A vendor stands by her chicken coop in Fuqing, southeast China's Fujian Province on April 26. At least 20 people have died from the virus which, while common in birds, hadn't been detected in humans before the first cases were reported in March.

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Bird flu scare spreads – A woman wearing a medical mask walks past vending machines that sell masks outside National Taiwan University Hospital in Taipei on April 26. A 53-year-old Taiwanese businessman has contracted the H7N9 strain of bird flu while traveling in China, Taiwan's Health Department said on April 24. It's the first reported case outside of mainland China. The man was hospitalized after becoming ill three days after returning from Suzhou on April 9.

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Bird flu scare spreads – Disease control workers examine a chicken in a poultry farm in Fuqing on April 26.

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Bird flu scare spreads – Three people wearing masks walk outside the National Taiwan University Hospital in Taipei on Thursday, April 25. China has reported 83 cases of H7N9 avian influenza.

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Bird flu scare spreads – An H7N9 bird flu patient walks in the corridor of a hospital after his recovery and approval for discharge in Bozhou, in central China's Anhui Province, on Friday, April 19.

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Bird flu scare spreads – Chickens line the walls at a poultry farm on Thursday, April 18, in Yuncheng, China.

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Bird flu scare spreads – A 7-year-old girl, who was the first confirmed bird flu case in Beijing, is discharged from Beijing Ditan Hospital on Wednesday, April 17.

Bird flu scare spreads – A man throws ducklings into a stove at a duck farm in Zhangzhou in China's Fujian province on Sunday, April 14. The farm has had to kill more than 400,000 newborn ducks every week after the H7N9 bird flu affected the domestic poultry market.

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Bird flu scare spreads – A woman uses a lamp to illuminate a batch of eggs in the hatchery of a duck farm in Zhangzhou on April 14.

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Bird flu scare spreads – Cheng Jun, vice president of Beijing's Ditan hospital, shows a video of the first bird flu victim in intensive care during a press conference on Saturday, April 13.

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Bird flu scare spreads – Officials in Hong Kong test poultry at the border with mainland China on April 11 as authorities step up measures against the spread of the deadly H7N9 bird flu.

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Bird flu scare spreads – Empty cages are seen at a closed bird market on April 10 in Shanghai.

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Bird flu scare spreads – A technician conducts tests for the H7N9 bird flu virus at the Kunming Center for Disease Control on April 10 in Kunming, China.

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Bird flu scare spreads – Medical workers take part in a drill that simulates human infection of the H7N9 bird flu virus on April 9 in Hefei, China.

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Bird flu scare spreads – People wear masks to protect themselves from the H7N9 virus, or bird flu, while riding the underground in Shanghai on Tuesday, April 9.

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Bird flu scare spreads – Employees work on the production line of Shufeng Jiedu Capsule, an herbal medicine for treating avian influenza patients, at a workshop of Anhui Jiren Pharmaceutical Co., Ltd on Monday, April 8 in Bozhou, China.

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Bird flu scare spreads – A public park staff carries a cage to catch pigeons at a public area in People's Square, downtown Shanghai on Saturday, April 6. Shanghai municipal government has ordered workers to remove pigeons from public area to prevent the spread of H7N9 bird flu to humans, local media reported.

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Bird flu scare spreads – A boy looks at pigeons at a public park in People's Square in Shanghaion on April 6. Health authorities in China said on Saturday that the country's 16 confirmed H7N9 bird flu cases were isolated and showed no sign that it is transmitted from human to human, Xinhua News Agency reported.

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Bird flu scare spreads – A public park worker catches a dove in People's Square in downtown Shanghai on April 6.

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Bird flu scare spreads – A public park worker places a dove in a cage in Shanghai on April 6.

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Bird flu scare spreads – A masked security guard stands outside Taipei Hoping Hospital on April 6, where new isolation units have been set up to treat potential new avian influenza cases.

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Bird flu scare spreads – Taiwan's Health Minister Chiu Wen-ta checks the negative pressure system in a isolation room as he inspects preparations for the virus in Taipei City Hospital Heping Branch, on April 6.

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Bird flu scare spreads – A woman wears a face mask inside a subway station in Shanghai, China, on Friday, April 5. The Chinese minister of agriculture said Thursday it had discovered the H7N9 virus in samples taken from pigeons at Huhai agricultural market, China's state-run Xinhua news agency reported.

Bird flu scare spreads – A policeman goes after a chicken that broke loose as Chinese health workers started culling chickens at Huhai wholesale market on April 5.

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Bird flu scare spreads – A woman cleans a birdcage at a store in Taipei, Taiwan, on Thursday, April 4.

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Bird flu scare spreads – Staff members from Taiwan's Center for Disease Control stand at the entrance of Sungshan Airport in Taipei.

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Bird flu scare spreads – A passenger has her temperature checked by a CDC staff member at the entrance of Sungshan Airport in Taipei.

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Story highlights

Authorities slaughter market birds in Shanghai after H7N9 found in pigeons

Poultry markets in Shanghai will close starting Saturday

Fourteen human cases of H7N9 have been reported in eastern China so far

No cases of human-to-human transmission virus have been confirmed

Chinese authorities have killed more than 20,000 birds from a live-poultry trading zone in Shanghai after an unusual strain of bird flu that has so far killed six people in the country was found in pigeons on sale in the city, state-run media outlet Xinhua reported Friday.

Details of the slaughter of chickens, ducks, geese and pigeons come as the city prepares to temporarily close all its live poultry markets. It wasn't clear how long the market closures -- announced Friday on the Shanghai Municipal Government's microblog account -- would last.

By Friday morning, authorities in Shanghai had already closed the Huhai agricultural market, where the H7N9 avian flu virus had been found in pigeons, Xinhua reported. The virus had not previously been found in humans until a series of cases were reported in China this week.

The cull at the Shanghai poultry trading zone came as researchers in the United States said they had started work on developing a vaccine for H7N9.

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At the Huhai market, Shanghai authorities were disinfecting the area and objects that came into contact with the birds, Xinhau reported.

Officials are trying to track where the infected pigeons came from.

A growing number of cases

A 64-year-old man died Thursday night in Huzhou, Zhejiang province, the provincial health bureau said Friday. He died hours after doctors had confirmed he had been infected with the H7N9 virus, it said.

He is one of the 14 human cases of H7N9 reported so far -- all of them in the coastal area of eastern China. Authorities there began reporting the first cases on Sunday. Four of the deaths happened in Shanghai, the two others in Zhejiang.

The ages of those infected have ranged from a 4-year-old child, who was reported to be recovering, to an 83-year-old man.

No cases of human-to-human transmission of the H7N9 virus have been confirmed so far.

A person in Shanghai who developed flu symptoms after coming into close contact with a patient who died of the virus tested negative for H7N9, city authorities said.

Seeking the cause and a vaccine

"We don't know yet where the humans got their virus from," said Dr. Joseph Bresee, who heads the epidemiology and prevention branch in the U.S. Centers for Disease Control and Prevention's (CDC) influenza division.

The virus has not been shown to spread easily between humans, he added.

The CDC, based in Atlanta, is working closely with Chinese authorities trying to find the source of the human infections, Bresee said.

"There are lots of things happening at CDC to prepare for this virus," Bresee said. "State health departments are readying themselves just in case," and researchers are working on developing a vaccine for this strain, he said.

In a sign of broader regional concern about the situation, the Hospital Authority in Hong Kong said it had sent a team of six people, including experts from Hong Kong University and the Center for Health Protection, to Shanghai on Thursday.

The team's purpose was to "learn about the experience of H7N9" in Shanghai, the authority said, adding that it was due to return late Friday.

And Japan's National Institute of Infectious Diseases will receive samples of the virus from Chinese authorities as soon as this month, CNN affiliate NHK reported. The institute is already analyzing genetic information from the virus in order to be ready to quickly produce vaccines, if needed, NHK said.

Other strains from the H7 virus family caused previous outbreaks in poultry in countries including the Netherlands, Britain, Canada, the United States and Mexico, Malik Peiris, a professor at Hong Kong University's School of Public Health, said earlier this week. Human infection was documented in all of those cases except the Mexican one.

The outbreak of the H7N7 strain in the Netherlands in 2003 infected 89 people, one of whom died, according to Peiris.

The better known H5N1 avian flu virus has infected more than 600 people since 2003, of which more than 370 have died, according to the World Health Organization.

In February, China reported two new human cases of H5N1 in the southern province of Guizhou, both of whom were in a critical condition, the WHO said.

A spike in H5N1 deaths, many of them children, has been reported in Cambodia, prompting concern among health authorities.